This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Currently, kidney function is assessed using the glomerular filtration rate which has limitations in adequately the predicting the level of kidney disease. The care of patients with chronic kidney disease would be improved by developing a dynamic tool that can better assess kidney function. The renal handling of orally ingested urea and the mechanisms of its'clearance can provide a more comprehensive diagnostic tool with which to evaluate kidney function and thereby initiate appropriate treatment.